The 23-year-old academy product tore his ACL earlier in the campaign and played only the final three matches of the season, including the FA Cup final defeat to Manchester City at Wembley. Despite the limited time available, his return made an immediate impression on those around him at the club.
Interim manager Calum McFarlane was effusive in his assessment after the Cup final.
"It has been fantastic to have Levi back, and it is also great news for English football. Here you have a really talented player with incredibly high potential."
Before his injury, Colwill was one of Chelsea's most important players. He started every match in the Club World Cup and provided the assist for Cole Palmer's second goal in the final with a long diagonal pass of considerable quality. His range of passing, composure on the ball and aerial ability at 6ft 2in make him the prototype for the modern centre-back the biggest clubs in Europe are currently seeking.
His inclusion in head coach Thomas Tuchel's preliminary England squad keeps alive the possibility of a first World Cup appearance, though the final 26-man list has not yet been confirmed. The timeline is tight after missing so much of the season, but his physical recovery appears ahead of schedule.
The uncertainty around his future stems from Chelsea's failure to qualify for the Champions League. Without European football, the club faces financial pressure and could be forced to sell assets to balance the accounts. Colwill is under contract until 2029 with an option for a further year, giving Chelsea leverage — but also giving him grounds to seek clarity on the club's ambitions.
Real Madrid have been linked with a number of left-footed centre-backs this summer. Barcelona, who face their own reconstruction challenges, are also understood to have noted his profile.